Pressure sensitive adhesive (PSA) articles are used in a wide variety of applications where there is a need to adhere to skin, for example, medical tapes, wound or surgical dressings, athletic tapes, surgical drapes, or tapes or tabs used in adhering medical devices such as sensors, electrodes, ostomy appliances, or the like. A concern with many of these adhesive articles is the need to balance the objectives of providing sufficiently high levels of adhesion while providing antimicrobial activity.
Approaches in the art to providing pressure sensitive adhesive articles with antimicrobial activity include depositing an antimicrobially effective layer of a silver salt on the adhesive surface of a wound dressing or incorporating an antimicrobial agent, e.g., iodine or chlorhexidine salts, into pressure sensitive adhesive microspheres prior to coating on a suitable wound dressing backing.
(Meth)acrylate pressure sensitive adhesives are attractive materials for many applications. (Meth)acrylates are known for their optical clarity, oxidative resistance, and inherently tacky nature. Inherently tacky (meth)acrylate pressure sensitive adhesives (i.e., materials that require no additives such as tackifying resins) are typically formulated predominately from acrylic acid ester monomers. Examples of such monomers include n-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, isononyl acrylate, isodecyl acrylate, and dodecyl acrylate. When these (meth)acrylate monomers are polymerized, the homopolymers have a glass transition temperature (Tg) of less than about 25° C. This low Tg is a necessary property in (meth)acrylate materials that exhibit tack at room temperature.
A means of reinforcing (meth)acrylate polymers is to copolymerize the (meth)acrylate monomers with acidic comonomers, such as acrylic acid, methacrylic acid, beta-carboxyethyl acrylate, itaconic acid, sulfoethyl acrylate, and the like. Addition of these acidic comonomers in minor amounts (e.g., about 1 weight percent to about 15 weight percent) can enhance the internal or cohesive strength of the PSA. This increased polymer reinforcement, however, can diminish the tack of the acidic comonomer-containing (meth)acrylate copolymer, which is often undesirable. Furthermore, there is a desire to eliminate such acidic components in pressure sensitive adhesives, particularly for use on skin. Such components can deactivate antimicrobial agents, for example.
Thus, there is a continuing need for pressure sensitive adhesives, particularly (meth)acrylate adhesives that can be used in medical applications, for example, that are either inherently antimicrobial and/or are compatible with added antimicrobial agents.